Focus on plant foods
It comes down to this: plants have less fat, more fibre, and more cancer-fighting nutrients. These three elements work together to support your immune system and help your body fight off cancer. They also help to support a healthy weight: being obese, along with smoking and being physically inactive, is a risk factor for a number of cancers.
The best diet for preventing or fighting cancer is a predominantly plant-based diet that includes a variety of vegetables, fruits, nuts, grains and beans. The less processed these foods are—the less they’ve been cooked, peeled, stripped of their nutrients, or otherwise altered from the way they came out of the ground—the better.
There are many ways to add plant-based foods to your diet. A nice visual reminder is to aim for a plate of food that is filled at least two-thirds with whole grains, vegetables, beans, or fruit – three-quarters may be even better. Dairy products, fish, and meat should ideally take up no more than a third of the plate. Keep in mind that you don’t need to go completely vegetarian. Instead, focus on adding “whole” foods. Just as important, try to minimize or reduce the amount of processed foods you eat. Eat an apple instead of drinking a glass of apple juice, for example. Or enjoy a small bowl of porridge with raisins instead of a raisin-oat biscuit – more volume to fill you up, too.
Simple tips for getting more plant-based foods in your diet
Breakfast: Add fruit and a few seeds or nuts to your whole grain breakfast cereal (porridge/Weetabix) or yogurt. Spread nut butter, like almond or pumpkin seed, on wholemeal toast and top with sliced bananas, or even berries.
Lunch: Eat a big green salad topped with your favorite beans, seeds and other combination of vegetables. Get in the habit of adding salad vegetables to your rolls, and choose wholegrain bread. Vegetable-based bean soup is a wonderful way to get in a couple servings of vegetables and fibre.
Snacks: Fresh fruit and vegetables. Grab an apple, clementine or banana on your way out the door. Raw vegetables such as carrots, celery, cucumbers, cauliflower, peppers, etc. are great with a low-fat dip such as hummus or raita. Keep a mix of nuts, seeds and a little dried fruit on hand for a quick, no-thought snack. Every now and then add a little dark chocolate to your nibbles stash.
Dinner: Add fresh or frozen vegetables to your favorite pasta sauce or rice dish. Top a baked white or sweet potato with steamed broccoli and yogurt or tahini, sautéed vegetables, or with tomato salsa. Replace creamy pasta sauces, with sautéed vegetables or tomato sauce made with healthy olive oil.
Dessert: Choose fruit instead of a richer dessert. Or nibble on a single square of best quality dark chocolate. The occasional ‘blow out’ dessert is fine but perfectly ripe fruit is delicious too.
Fill up on fibre
Another benefit of eating plant-based foods is that it will also increase your fibre intake. Fibre, also called roughage or bulk, is the edible part of plants (grains, fruits, and vegetables) that your body can’t digest but where many nutrients are found and used by the body. Fibre plays a key role in keeping your digestive system clean and healthy by providing healthy bacteria and promoting regular bowel habits. It helps keep food moving through your digestive tract, and assists in removal of cholesterol and cancer-causing compounds before they can cause harm.
Fibre is found in fruits, vegetables, and whole grains. In general, the more natural and unprocessed the food, the higher it is in fibre. There is no fibre in meat, dairy, sugar, or “white” foods like white bread, white rice, and pastries.
Simple ways to add more fiber to your diet:
Use beans and lentils instead of meat in many dishes such as spaghetti Bolognese, chili, casseroles, stews, tacos, and even burgers (try half bean and half meat too).
Cut down on meat
Research shows that the less meat we eat the less risk from a variety of cancers. So what’s the link between meat and cancer risk? First, meat lacks fibre and other nutrients that have been shown to have cancer-protective properties. What it does have in abundance, however, is fat—often high levels of saturated fat. High-fat diets have been linked to higher rates of cancer overall. High levels of heme iron (what makes meat red) has recently been linked to the development of some gut cancers. Finally, depending on how much is eaten and how it is prepared, meat can promote the development of gut-based carcinogenic compounds such as N-nitroso compounds and heterocyclic amines. Even so, moderate amounts are considered by many health experts to be part of a healthy, balanced diet, providing first-class protein, B vitamins and iron.
Making better meat and protein choices
You don’t need to cut out meat completely and become a vegetarian. But most people consume far more meat than is healthy. The World Cancer Research Fund advises that we eat no more than 500 grams of cooked red meat (about 700 grams of uncooked) a week. Poultry, fish, seafood, beans, eggs and nuts make a great protein base for most meals. Look out for good quality, leaner cuts when buying red meat.
Eat red meat only occasionally. Red meat is high in saturated fat and has no fibre – eat it sparingly.
Reduce the portion size of meat in each meal. The portion should be able to fit in the palm of your hand, about 100 g.
Add beans and other plant-based protein sources to your meals.
Avoid processed meats such as hotdogs, sausages, bacon, and deli meats such as dried sausages and other salted and cured meats. These meats are generally full of saturated fats and salt, as well as preservatives that are known to be harmful to human health in quantity. See the AICR cancer prevention guidelines for more information.
Choose your fats wisely
A major benefit of cutting down on the amount of meat you eat is that you will automatically cut out a lot of unhealthy fat. Eating a diet high in fat increases your risk for some cancers. But cutting out fat entirely isn’t the answer either. In fact, some types of fat not only help us absorb fat-soluble vitamins but may actually protect against cancer. The trick is to choose your fats wisely and eat them in moderation.
Fats that may increase cancer risk – The two most damaging fats are saturated fats and trans fats. Saturated fats are found mainly in animal products such as red meat and whole milk dairy products. Trans fats, also called partially hydrogenated oils, are created by adding hydrogen to liquid vegetable oils to make them more solid and less likely to spoil—which is very good for food manufacturers, but not good for us.
Fats that may decrease cancer risk – The best fats are monounsaturated fats, which come from plant sources and when processed are liquid at room temperature. Primary sources include olives, olive oil, rapeseed oil, nuts/seeds and avocados. Also focus on omega-3 fatty acids, which fight inflammation and support brain and heart health. Good sources include salmon, tuna, trout, mackerel, anchovies, herring and flaxseeds.
Help with choosing the right fats
Watch your consumption of red meat, whole milk and butter as these are the primary source of saturated fats. Eggs have saturated fat too but they are also a source of important nutrients, including the hard-to-get Vitamin D. Butter in modest amounts, although a source of saturates, is more easily handled by the body than most margarines.
Cook with olive oil instead of regular ‘no-name’vegetable oil. Rapeseed oil is another good choice, especially for baking. Use other oils for drizzling and flavouring cooked foods (e.g. sesame, argan and walnut oils).
Check the ingredient list on food labels and try and avoid anything with hydrogenated or partially hydrogenated oils, which can be found in margarines, baking fats, salad dressings, and many packaged foods (chilled and ambient). Some supermarkets and major manufacturers have banned these fats, so there is a choice.
Trim the fat off of meat and poultry when you do eat it.
Add nuts and seeds to cereal, salads, soups, or other dishes. Good choices include walnuts, almonds, pumpkin seeds, hazelnuts, pecans, and sesame seeds. Brazils are great too but because of their very high selenium content, we should keep them to no more than 3 a day.
Limit fast food, fried foods, and packaged foods, which can be high in trans fats. This includes foods like crisps, sweet and savoury biscuits and pies, crackers, chips and pastries.
Eat fish once or twice a week. Choose at least one oily fish a week: good choices include wild Alaskan salmon (healthier than Atlantic), sardines, herring, trout and mackerel. Tinned mackerel and red salmon are fantastic store cupboard staples. White fish are low in fat and great for protein and some types have a smidge of Omega 3 fats.
Actively choose cancer-fighting foods
There are many things you can eat to maximise the strength of your immune system, as well as many cancer-fighting foods. But keep in mind that there is no single miracle food or ingredient. Research shows that most of the antioxidants and phytochemicals found in plant foods work best in combination. Eating a colourful and varied plant based diet may optimise dietary protection.
Boost your antioxidants. Antioxidants are powerful vitamins that help protect against cancer and assist the cells to function optimally. Vegetables and fruits are the best sources of antioxidants such as beta-carotene, vitamin C, vitamin E, and selenium. Supplementation has not been shown to be useful and may even be harmful in some instances. Naturally obtained nutrients are better for us, tastier and cheaper, too.
Eat a wide range of brightly coloured fruits and vegetables. Colourful fruits and vegetables are rich in phytochemicals – potent disease–fighting and immune–boosting nutrients. The greater the variety of colours – and tastes – you include, the more you will benefit, since different colours and taste types are rich in different phytochemicals.
Flavour with immune-boosting spices and foods. Garlic, ginger, black pepper and turmeric not only add flavour, but they add a cancer-fighting cache of valuable nutrients. All fresh herbs and dried spices will have phytochemicals. Use them in soups, salads, casseroles, or any other dish, especially in place of salt.
Drink plenty of water. Water is essential to all bodily processes. It stimulates the immune system, removes waste and toxins, and transports nutrients to all of your organs. Have it as green and black teas too. Coffee is fine in moderation and due to its polyphenol content may even be actively helpful.
Aim for two-thirds to three-quarters of the daily diet to be from plant foods. This leaves plenty of room for good quality meat and fish, as well as treats.
Pay attention to food preparation
Choosing healthy food is not the only important factor. It also matters how you prepare and store your food. The way you cook your food can make a difference to the amount of nutrients we absorb and how safe our food is for us.
Preserving the cancer-fighting benefits of vegetables
Try to eat some raw fruits and vegetables. These tend to have the highest amounts of vitamins and minerals, although cooking some vegetables can make the vitamins more available for our body to use. During treatment you may find it easier on your digestion to have your vegetables peeled and cooked, or juiced. See my page on juicing and try my quite fabulous Beetroot Zinger.
When cooking vegetables, steam until just tender using a small amount of water. This preserves more of the vitamins. Overcooking vegetables leaches out the vitamins and minerals. For an extra vitamin boost, use the vegetable cooking water in a soup or another dish.
Wash all fruits and vegetables. Use a vegetable brush for washing. Washing does not eliminate all pesticide and germ residue, but will reduce it.
Cooking and carcinogens
Carcinogens are cancer-causing substances found in our environment but also in food. Carcinogens can form during the cooking or preserving process—mostly in relation to meat—and as foods start to spoil. Examples of foods that have carcinogens are cured, dried, and preserved meats (e.g. bacon, sausage, biltong); burned or charred meats; smoked foods (including smoked salmon); and foods that have become mouldy. Here are some ways reduce your exposure to carcinogens:
Do not cook oils on high heat. Low-heat cooking or baking (less than 200C) prevents oils or fats from becoming carcinogenic. Instead of deep-frying and high heat pan-frying, opt for healthier methods such as baking, boiling or steaming.
A healthier stir-fry. Instead of ultra-high temperature stir frying try adding a small amount of oil to a cold wok, along with an equal amount of water. Gradually heat until starting to sputter. Add in your recipe’s ingredients and turn up the heat, stirring quickly to reduce contact with the wok. This method is thought to reduce the molecular changes that can occur in oils at very high temperatures.
Barbeque with caution. Burning or charring meats creates carcinogenic substances. If you do choose to barbeque, don’t overcook the meat and be sure to cook at the proper temperature (not too hot!). You may like to start the meat on the grill (to get the marks) and finish cooking it in the oven. They will be juicier that way too.
Store oils in a cool dark place in airtight containers; they quickly go off when exposed to heat, light or air.
Avoid foods that look or smell mouldy, as they likely contain aflatoxin, a strong carcinogen. Aflatoxin is most commonly found on mouldy nuts. Nuts will stay fresh longer if kept in the refrigerator or freezer.
Recommended Reading: American Institute for Cancer Research “CancerResource: Living With Cancer” downloadable handbook – for during treatment and post-treatment guidance